Without limiting the scope of the invention, its background is described in connection with MALDI matrices and sample preparation techniques.
U.S. Pat. No. 7,202,472 issued to Schmucker et al., 2007 relates to an improved method for mass spectrometric analysis, in particular for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) using nanoparticles. In the Schmucker patent an analyte is added to a nanoparticle suspension, and the suspension containing the bound analyte is then deposited directly on a MALDI sample carrier and investigated by mass spectrometry, and to a nanoparticle suitable for this method.
U.S. Patent Application No. 2010/0090105 (Liang et al., 2010) discloses a plate for matrix-assisted laser desorption ionization (MALDI) mass spectrometry comprising an electrically conductive substrate (1) covered with a light sensitive matrix (2), the matrix (2) comprising a light absorber, a charge carrier, a probe molecule and a photo-sensitizer (3) arranged to oxidise the probe molecule when irradiated with light (4). The light sensitive matrix in the Liang invention comprises a xerogel containing semi-conducting nanoparticles and the photo-sensitizer comprises semi-conducting nanoparticles that absorb light at a wavelength substantially equal to that used for matrix-assisted laser desorption ionization. The semi-conducting nanoparticles of the Liang invention comprise titanium dioxide, zinc oxide or cadmium selenide.
U.S. Pat. No. 7,122,792 issued to Chen et al., (2006) provides a simple, rapid and cost-effective metal oxide-assisted laser desorption/ionization mass spectrometry (MOALDI MS) without the addition of light-absorbing organic-matrix, comprising the use of (a) an inorganic metal oxide with light absorbing capability as an assisting material to render desorption/ionization of samples in laser desorption/ionization mass spectrometry and (b) a citric acid buffer as the proton source for enhancing the ionization efficiency for analytes. Metal oxide assisting materials is not only restricted to the uses of films. Metal oxide nanoparticles are also suitable to be used as the assisting materials. Low matrix background, stable surface feature, homogeneous sample deposition, and wide detectable mass range are the merits of MOALDI MS.